Automated Storage and Goods-to-Person
Modern distribution centers, as well as production kitting operations, are realizing greater productivity and efficiency with improved worker ergonomics by combining automated storage with goods-to-person processes.
“Goods-to-person” means that the order picker stays at a workstation, and the automated storage and retrieval system (ASRS) brings the goods or SKUs (the stock keeping units) to the person. The SKU is removed from the storage container at the workstation and then sent back to the automated storage and retrieval system. The basic system components consist of an automated storage and retrieval sub-system for the product inventory; the workstations; a conveyance method to bring the SKUs to the workstations; and software to synchronize and control the flow of inventory.
The automated storage and retrieval technology that most often supports goods-to-person systems include Multishuttle, AutoStore and Miniload.
- Multishuttle consists of multiple levels of racking, automated shuttles on every level, software and controls. The automated shuttle travels horizontally to access loads stored in the rack structure—typically totes or cartons.
- AutoStore consists of storage bins, robotic bin movers, a grid support structure and software. The robotic bin movers drive on top of the grid to access inventory stored in the bins below. The bins are put away, retrieved and delivered to the workstations, as required. There are no dedicated access aisles, so the entire cube can be used to store product.
- Miniload is a “machine-in-aisle” storage and retrieval subsystem. It is most often applied when there is a need to accommodate large quantities of inventory. The Miniload uses a flexible load-handling device that supports a wide range of tote and carton sizes.
Benefits of Goods-to-Person Order Fulfillment with ASRS
Significant benefits are realized with the use of the ASRS and goods-to-person methodology. Even though there are many variations on how a system is configured, the benefits are universal:
Eliminate picker travel time, use less labor—Order pickers do not need to roam the warehouse walking to and from the dedicated pick faces. Travel time is the largest time component of a traditional order picker in a person-to-goods arrangement. By minimizing this time component, productivity is increased and labor to operate the facility is reduced.
Omit the dedicated pick face—A goods-to-person system involves staging the inventory in an automated storage and retrieval system. The inventory or SKUs are retrieved when required at a workstation. This omits the need for SKU slotting and re-slotting, the re-location of dedicated pick faces as SKU velocity changes, which are typical of a “person-to-goods” warehouse.
Reduce system footprint—The space required for an ASRS and goods-to-person configuration is less than conventional person-to-goods method. With the inventory in an ASRS, significant space savings can be achieved. A typical footprint is approximately 50% less than conventional storage.
Product Security—When the product inventory is placed into a high density ASRS, it is secure and only available to the appropriate warehouse staff at the workstations. Product security is important to maintain inventory accuracy, reduce theft and assure first-in/first-out or first-in/first-expired strategies.
Ergonomic workstations—The order picking workstations are designed for employee comfort. Working heights, range of motion and environment (lighting, temperature) are optimized for the employee. Workstation design omits the requirement to move and lift totes/cartons. Furthermore, workstations are designed to support special needs employees and allows universal access.
Speed in order selection—The workstation design allows high worker productivity. Since there is little or no travel time, and the items to be picked are ergonomically served to the worker, high rates of order selection are achieved. Most operations obtain rates in the 300 to 800 order lines per hour per operator. For applications where low-velocity inventory is placed in a goods-to-person arrangement, fast-moving inventory can be isolated into a fast-pick sub-system. Not restrained by picking slow movers, the fast-movers picking sub-system is even more efficient.
Accuracy—Order picking using a goods-to-person workstation is more accurate, because operators are typically handling one SKU at a time—making the potential for errors less likely. Most goods-to-person stations utilize put-to-light technology to indicate quantity and location to put the items, further enhancing accuracy. The picking process is performed by one person, thereby enabling QC traceability.
De-coupled workstations—Staff can work in parallel, unaffected by each other. Workstations can be opened and closed according to business volume on a particular shift of operation. There is redundancy in this configuration since items can be processed at any location, as the workstations are completely decoupled.
High utilization workstations—Work flows into the pick station smoothly and consistently. Order pickers are highly utilized, since they do not need to wait for work. Worker productivity is not affected by the structure typical of a traditional pick module. For example, in traditional pick modules, there may be high activity in one zone; little activity in another zone; or there may be pace issues in a pick-and-pass environment, etc.
Sequencing—When building a customer order, SKUs are removed from the ASRS and then flow to each workstation in a precise sequence. For example, items can be presented to the order selector by weight: heavy to light. In another example, orders can be built in sequence by family group or by truck delivery route.
Order Profile—The system is not affected by changes in order profile. For example, single item orders and multi item orders are accommodated with equal efficiency. This means that trends, such as more orders with fewer order lines, do not compromise productivity. This feature adds to the ability of goods -to-person systems to accommodate change as order profiles change in the future.
ASRS Accommodates SKU Growth—If more SKUs are added, the ASRS can absorb the new loads or the system can be expanded with additional automated storage modules, or existing modules can be extended.
Examples of Goods-to-Person Implementations with ASRS
There are many warehouse operations that utilize goods-to-person order fulfillment with ASRS. These applications have the appropriate activity profile and business drivers to realize the benefits.
A personal care products distributor was picking slow- and fast-moving inventory using paper pick lists in a person-to-goods arrangement. There was an unacceptable level of errors in inventory; there were order accuracy issues. This operation implemented a goods-to-person system for medium- and slow-moving inventory and a separate pick to light sub-system to accommodate the very fast-moving inventory. The goods-to-person system provides pick rates of up to 850 order lines per hour per pick station, while reducing picking errors by more than 75% with the one to one pick arrangement. Furthermore, the SKUs are stored in a high-density ASRS that reduced the system footprint by more than 50%.
A pharmaceutical distributor needed to improve order accuracy, increase productivity and decrease order processing time. A goods-to-person system was implemented that utilized an automated storage and retrieval system to stage the inventory, one replenishment station, two pick stations and four packing stations. Picking errors were reduced from 1% to less than .01%. The staff to operate was reduced, since each pick station can now obtain 400 lines per hour. In addition, product security was increased by staging the inventory in an automated system, thereby reducing access to narcotics. Also, product retrieved from the ASRS and presented to the order picker can be sequenced; heavy, light, liquid, etc.
An industrial supplies distributor implemented a goods-to-person order fulfillment system and experienced improved intra-logistics results. First, order cut off time was extended by three hours, since order processing time was decreased from 3.5 hours to 30-60 minutes. Also, reduced order processing time allowed more time to bundle orders for shipment and reduce shipping rates. The picking process is performed by one person, thereby improving traceability. Finally, the system offers redundancy as items can be processed at any location as the workstations are completely decoupled.
Goods-to-person order fulfillment with automated storage is often implemented when the user’s business objectives link to the benefits: need for product security/accuracy, lack of space, need for productivity/efficiency and worker ergonomics. A typical user profile may have a split case picking operation; 5,000 or more orders per day; and a high quantity of slow-moving inventory, typically 10,000 or more SKUs. This method is not industry specific, but rather, it fits a wide array of market sectors. Industry sectors that have successfully implemented goods-to-person systems with ASRS include distributors of: books, pharmaceuticals, retail grocery, retail general merchandise, retail apparel, meat, dairy products, industrial parts, medical equipment and personal care items to name a few. WMHS